Mine roof support control system

ABSTRACT

Mine roof supports have a fluidic logic control system for raising and lowering the supports and for advancing the supports in the form of a number of units one on each support. Each unit has a first OR gate which controls a first interface valve to cause the support to lower and advance itself, a second interface valve causing the support to rebrace itself controlled by a second OR gate interconnected with the first through an AND gate which receives inputs from the first OR gate and a sensor denoting that the advance has been completed, an AND gate receiving inputs from a sensor denoting that the support is rebraced and from the second OR gate to provide an input for the first OR gate of the next unit and a reset signal which is passed through a delay restrictor to reset the first OR gate of the support.

United States Patent Cooper [54] MINE ROOF SUPPORT CONTROL SYSTEM [72] Inventor: Kenneth Cooper, Orrell, near Wigan, En-

gland Gullick Dobson Limited, lnce, Wigan, England 22 Filed: Mar. 17,1970

21 Appl.No.: 20,324

[73] Assignee:

[58] Field ofSearch ..6l/45 D; 299/1; 91/41 1,412, 91/414, 36, 37,170 MP [56] References Cited UNITED STATES PATENTS 3,216,201 11/1965 Kibble et a1 ..61/45 D 1 May 23, 1972 Primary ExaminerDennis L. Taylor Att0rneyBerman, Davidson & Berman [57] ABSTRACT Mine roof supports have a fluidic logic control system for raising and lowering the supports and for advancing the supports in the form of a number of units one on each support. Each unit has a first OR gate which controls a first interface valve to cause the support to lower and advance itself, a second interface valve causing the support to rebrace itself controlled by a second OR gate interconnected with the first through an AND gate which receives inputs from the first OR gate and a sensor denoting that the advance has been completed, an AND gate receiving inputs from a sensor denoting that the support is rebraced and from the second OR gate to provide an input for the first OR gate of the next unit and a reset signal which is passed through a delay restrictor to reset the first OR gate of the support.

5 Claims, 4 Drawing Figures PATENTEDMAY 2 3 I972 SHEU l- UF 3 INVENTOR: KEN/V5 7-H COOPER,

, PATENTEUMAY 23 m2 3,664-,1 88

INVENTOR:

KEN/V5 TH COOPER,

ATTORNEYS.

MINE ROOF SUPPORT CONTROL SYSTEM The present invention concerns a control system for self-advancing hydraulic mine roof supports.

A4. Legs Raise A5. Rear and Middle Legs Lower The interface valves are diaphragm-operated valves and there are five of these in all since all the legs can be raised by a A self-advancing mine roof support sometimes consists of single interface valve, selection of which legs are raised being two support units which are normally both extended against a mine roof but can be advanced by lowering one unit, pushing it forward by means of an advancing ram, re-setting the unit, and lowering the other which is drawn forward by means of the advancing ram and then reset. Another form of mine roof support first pushes a conveyor forward and then lowers itself from the mine roof and pulls itself forward to the conveyor and then resets itself against the roof.

These roof supports are used in a line along a coal face and are advanced in turn under manual control. A control unit to initiate the various operations to advance a single support and after that operation is completed to advance the succeeding one in the line may be desired.

According to the present invention there is provided a control system for self-advancing mine roof supports consisting of fluidic logic elements.

There are several types of fluidic logic elements but the perferred form of fluidic logic element is that type relying on wall attachment effects, sometimes referred to as the coanda effect.

While the control system can be designed to carry out the complete sequence automatically it is safest in manned faces to advance the conveyor or the foremost of the support units under direct manual control and only to bring up the support to the conveyor or rearmost of the support units to the foremost by automatic control.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a side view of a roof support,

FIG. 2 is a hydraulic circuit diagram for the roof support of FIG. 1,

FIG. 3 is a block diagram of a control system and FIG. 4 is a diagram illustrating the logic used in the system of FIG. 3. v

The specific embodiment is a system for controlling a line of mine roof supports, three of which N, NH and N+2 are shown in FIG. 3. Each roof support is'as shown in FIG. 1 and consists of a canopy b and a base 10a urged apart by three pairs of side-by-side legs 10. Each leg 10 is a hydraulic pistonand-cylinder device and another piston-and-cylinder device (the advancing ram) 11 is disposed in the base for pulling or pushing by means of an attachment 11b on a conveyor C. The ram 11 is anchored to the base by brackets 11a.

0n the support there is a hydraulic control box 9 (see FIG. 2) which includes, three valves 15, a valve 16 and a hydraulic impedance 17. Only one valve 15 is shown as the other two are identical. Each valve 15 or 16 comprises a closure member 22 or 23 resiliently biassed to seal an aperture or 21 and which can be dislodged by a piston 18 or 19. Each pair of legs 10 is connected through a line 14 and the valve 15 to a line 26. The valve is opened by pressure applied along lines 28 and 24 to the piston 18. The pressure in line 28 is also applied through the impedance 17 to open the valve 16 but because of the impedance 17 this valve 16 opens after valve 15. When the valve 16 is open the pressure in line 28 is applied along line 27, through the valve 16 and line 12 to the ram 11. An alternative input can be applied to the ram 11 through line 13.

The control box also includes a unit of a fluidic logic system illustrated in FIG. 4. The supports are powered with hydraulic fluid from lines 31 and there are also fluidic logic lines 32. The lines 32 are compressed air lines.

Interface valves between low pressure air and high pressure hydraulics are required as follows:

Al. Rarn Pull A2. Ram Push A3. Front Legs Lower achieved by the legs lower interface valves A3 and A5.

External inputs are provided by eight push buttons:

B1. Start B2. Stop B3. Push B4. Pull B5. Lower Front Legs B6. Lower Middle and Rear Legs B7. Raise Front Legs B8. Lower Middle and Rear Legs.

Also there are two additional automatic external inputs provided by sensors which indicate:

S1. Advance complete S2. Legs set Advance complete is given when the ram has fully retracted or pulled as sensed by a positional sensor 51. Legs set is given when a pressure of approximately 2,000 psi. has been obtained in the legs as sensed by the pressure sensor S2.

It will be appreciated that the word interface is used in the sense of a means for controlling a hydraulic working fluid from the low level fluidic logic signals.

The interface valves A1, A2, A3, A4 and A5 are used respectively to apply pressures to line 28, line 13, the valve 15 for the front legs, line 26 and the valves 15 for the rear and middle legs. Valves A5 are not shown in FIG. 2 but would take the place of the valve A3 in association with the two other valves 15. Because valves Al and A3 or A5 both apply pressure to a single valve 15 it is necessary to decouple them and this is done by having an additional piston 18a sliding in its own sealed compartment. Each valve A3 or A5 is associated with a single pair of legs but the valves A1, A2 and A4 are associated with the support as a whole. FIG. 2 illustrates diagrammatically that the valves Al to A5 connect alternatively to an outlet 33 or to a pressure source 34.

Since basically the circuit of FIG. 4 comprises an interconnected array of gates, it is clearer to describe the circuit in terms of the functioning of the control system.

Considering one N of the supports N, N+l or N+2 the circuit of FIG. 4 functions in the following manner.

When air is first applied to the power inputs of the system it is essential that a bistable switch D sets up in a manner such that an OR gate does not cause a RAM PULL operation. To achieve this an OR/NOR gate G is added. From FIG. 4 it can be seen that if the switch D sets up incorrectly so as to operate an OR gate F to cause a RAM-PULL" operation a signal from the NOR output of the OR/NOR gate G would pass through the OR gate B and cause the switch D set up in the desired state. Once the switch D achieves this state the OR/NOR gate G switches to the OR output which is fed back onto the gate G thus latching the gate G in the OR state. The gate G therefore is only a one shot device to enable the switch D to set up in its desired state when the air is first turned on.

Assuming then the air to be turned on and the switch D to be in its correct state, the start button B1 can be pressed to provide a sequence initiating signal.

This causes the OR gate A to switch to the OR output thus causing the switch D to switch and remain in this state. The output from the switch D is now split to feed the OR gate F and the two input AND gate E. Since the ram is fully extended and therefore cannot be fully retracted the Advance Complete signal from the sensor S1 is not present on the AND gate E, therefore there is no output from the gate E.

The OR gate F however, will switch to give an output at the OR leg. This output is fed to the RAM PULL interface valve Al which in turn applies pressure on the line 28 to operate the valve 16 causing the ram device 1 l to retract or PULL. The hydraulic circuit is also such as to cause the interface valve Al to operate the three valves 15 which isolate the legs of a mine roof support.

This feed therefore also operates the leg isolating valves 15 causing them to open and thus the legs to lower. The support is now being pulled across with the legs lowering. On completion of the pulling stroke the sensor S1 is operated and a further signal (ADVANCE COMPLETE) is fed into the AND gate E. The inputs to the gate E are now both present which causes the gate E to give an output at the AND output. This output is fed to an OR gate J and an AND gate H. Since the legs are lowering the pressure in them will not be at its maximum value therefore there will be no input to the gate H from the sensor $2; the AND gate H therefore remains closed.

The OR gate J however, which is a four input device, will give an output at the OR leg. This output is fed to the LEGS RAISE interface valve A4. Operation of this valve feeds pressure on the lines 26 to the isolating valves 15. These valves are still open due to the pilot pressure from the RAM PULL operation and consequently the pressure will be fed to the legs 10 causing them to extend. When the legs have reached maximum stroke and the pressure built up to its maximum, the pressure sensor S2 will operate giving the PRESSURE SET" signal. This causes the AND gate H to give an output at the AND output.

This output is now fed to the re-set side of the switch D through OR gates B and C and a restrictor R. It is also fed to the set side of a switch D on support N+l, via a 9 feet inch length of :41 foot diameter piping and an OR gate A on the support N+1. It is essential that switch D on the support N+l sets before the switch D on the support N resets because otherwise the initiating signal to the support N+l would terminate. This is the reason for the fitting of the restrictor R.

Once the signal passes from the support N to the support N+l the sequence is exactly the same, the signal then passes to the support N+2 and so on. This completes the automatic circuit the remaining devices and push buttons are to give manual operating facilities. These push buttons are as follows:

Stop Button B 2 resets the switch D through the OR gate C and thus de-energizes the gate F.

Legs Raise Front Button B 3 operates a four input OR gate J and an OR gate L. Operation of the gate L actuates the interface valve A3 to cause the isolating valve 15 for the front pair of legs to open and operation of the gate J actuates the interface valve A4 to feed pressure to this valve, the result being to cause the legs to raise.

Legs Lower Front Button B 4 controls the OR gate L causing the isolating valve 15 for the front pair of legs to open to the pressure relief line and hence the legs will lower under their own weight.

Legs Raise Rear and Middle Button B 5 operates the four input OR gate M. This has the same effect as the button B 3 except that the OR gate M actuates interface valve A 5 to open the isolating valves for the Rear and Middle Legs.

Legs Lower Rear and Middle Button B 6 actuates the OR gate M only causing the isolating valves to open to a pressure relief line and hence the legs will lower under their own weight.

Ram Pull" Button B 7 operates the OR gate F and the four input OR gate J. This enables the ram to be pulled without lowering the legs.

Ram Push Button B 8 controls an AND gate K. Providing the legs are set and a signal PRESSURE SET" is present on the AND gate K, the gate will operate and cause the ram to extend or PUSH. It is essential when pushing that the legs are set hence the necessity for the safety interlock feature of the AND gate K. This pushes the conveyor forward under manual supervision and thus avoids a possible hazard. The gate K is interlocked by gates 0. Q1, Q2 and P. The gates Q1 and Q2 form a three-way OR gate for locking the gate 0 into an OI-"F" state from which it is to be moved to an ON" state by actuation of the push button B8 to apply the push button signal to the gate K. The gate P merely ensures that the gate 0 is initially in the off position. If gate 0 is originally ON and gate P original] OFF a signal is fed to the gate O1 to return the gate to OFF. As soon as the gate P is set to ON", it locks itself out of the circuit. The other two inputs of the gates Q1 and Q2 are derived from the gate A and the gate C so operation of either of push buttons B1 or B2 overrides push button B8.

It is possible to dispense with some of the gates by using biassed gates which assume a predetermined condition on initially switching on.

The invention is not limited to the specific embodiment. Many modifications are possible. To adapt the invention to supports using double acting legs, the valve A4 would be twinned so that one end of the leg would be supplied with pressure fluid whilst the other was vented and the valve 16 and restrictor 17 omitted so line 28 would feed into line 12 directly.

I claim:

1. A control system (for self-advancing mine roof supports) consisting ofa plurality of identical units for mounting each on one of the supports, each unit comprising a plurality of pneumatic fluidic logic elements interconnected to perform a sequence of operations, one of the logic elements being connected to provide an initiating signal to a logic element of a subsequent unit characterized by the initiating-signal-providing-element also being connected through a delay restrictor to provide a reset signal to its own unit after the subsequent unit has been initiated.

2. A control system according to claim 1 having at least one sensor to detect the end of an operation.

3. A control system according to claim 1 consisting of a number of units each adapted for mounting on a mine roof support comprising in each unit:

an interface valve for causing the associated support to release itself from the roof of a mine working and to advance, a first fluidic OR gate controlling said interface valve, an initiating signal pneumatic line and a push button to provide alternative initiating signals to said OR gate, a first sensor for detecting the end of the advance of the support, an interface valve for causing the support to rebrace itself against the roof of a mine working, a second fluidic OR gate controlling this interface valve, interconnecting means including a first fluidic AND gate receiving one input from the first OR gate and a second input from said first sensor, a second sensor for detecting the support has been rebraced, a second fluidic AND gate receiving one input from said second OR gate and one from the second sensor to apply an initiating signal over the pneumatic line of the following unit, and reset interconnections including the delay restrictor from said second AND gate to said first OR gate.

4. A control system according to claim 3 further comprising manually operable means for pushing an anchorage away from said support.

5. A control system according to claim 2 further comprising interlocking means for ensuring the safety of said pushing. 

1. A control system (for self-advancing mine roof supports) consisting of a plurality of identical units for mounting each on one of the supports, each unit comprising a plurality of pneumatic fluidic logic elements interconnected to perform a sequence of operations, one of the logic elements being connected to provide an initiating signal to a logic element of a subsequent unit characterized by the initiating-signal-providingelement also being connected through a delay restrictor to provide a reset signal to its own unit after the subsequent unit has been initiated.
 2. A control system according to claim 1 having at least one sensor to detect the end of an operation.
 3. A control system according to claim 1 consisting of a number of units each adapted for mounting on a mine roof support comprising in each unit: an interface valve for causing the associated support to release itself from the roof of a mine working and to advance, a first fluidic OR gate controlling said interface valve, an initiating signal pneumatic line and a push button to provide alternative initiating signals to said OR gate, a first sensor for detecting the end of the advance of the support, an interface valve For causing the support to rebrace itself against the roof of a mine working, a second fluidic OR gate controlling this interface valve, interconnecting means including a first fluidic AND gate receiving one input from the first OR gate and a second input from said first sensor, a second sensor for detecting the support has been rebraced, a second fluidic AND gate receiving one input from said second OR gate and one from the second sensor to apply an initiating signal over the pneumatic line of the following unit, and reset interconnections including the delay restrictor from said second AND gate to said first OR gate.
 4. A control system according to claim 3 further comprising manually operable means for pushing an anchorage away from said support.
 5. A control system according to claim 2 further comprising interlocking means for ensuring the safety of said pushing. 